Survey Confirms Native Freshwater Fish Stocks Are Declining

This week's International River Symposium, which ends in Perth today, has been told that native freshwater fish species have been found in less than half of the lakes recently surveyed in Western Australia.

The survey, funded by the Natural Resources Management (NRM) project, examined the biodiversity of freshwater fish in lakes in the South West and Mid West during the past twelve months. Of the 114 lakes surveyed, only 50 contained native freshwater fish species.

Dr Craig Lawrence, Freshwater Fish Scientist at the Department of Fisheries, said scientists had expressed concerns at the loss of habitat for native freshwater species for many years, with 80% of water bodies lost to land reclamation and urban infill since European settlement.

"The NRM survey results confirms the trend is still continuing, with half of the permanent water bodies, listed on maps in the year 2000, no longer containing water throughout the year," Dr Lawrence said.

"With the loss of water bodies, we anticipated that native freshwater fish were under pressure, but for the first time we are getting a clear picture of the situation and the results are concerning."

Dr Lawrence said the large number of introduced fish found during the survey was also a concern because they competed with native fish for food and habitat.

"Only nine per cent of the lakes were populated exclusively with native freshwater fish," he said.

"Introduced freshwater fish species were found in 66 per cent of the lakes and 12 per cent of the lakes surveyed had no fish at all."

Dr Lawrence said the Department of Fisheries would use the information, derived from this survey, to develop both a risk based approach to deal with the problem of introduced fish species, along with an education campaign to inform the public of the environmental risks associated with releasing non-native fish into WA's water bodies.

"We will also work closely with other agencies and the community, to address issues of water quantity and quality and a possible native fish restocking program," he said.

"The Department's native fish breeding program, combined with the University of Western Australia's genetics research, puts us in a good position to seriously consider producing native freshwater fish species for restocking water bodies."